The present invention relates to a matrix for filling a tooth whereby the matrix comprises a strip for surrounding the tooth for filling a lateral cavity. The matrix comprises a wedge connected to the strip for applying pressure onto the space between adjacent teeth.
Such a matrix, is for example, known from German Published Patent Application 38 16 501. Such a matrix has a strip that can be inserted into the space between two adjacent teeth. A wedge is formed on the strip and serves to force the strip onto the tooth to be filled.
Such a matrix is used to fill lateral cavities of a tooth. While for central cavities, in general, a uniform and excellent connection to the surrounding dentin is possible, the matrix strip for lateral cavities simulates the surrounding dentin and thus is designed to realize a closely fitting and gap-free filling.
It is also known to provide matrix strips of an annular design that are to be tightened by a matrix tensioning device so as to force the metallic band in a secure manner against the tooth to be filled.
However, the prior art matrix has the disadvantage that the contact of the matrix strip at the tooth to be filled in the area of the cavity is usually unsatisfactory. Especially when the dentist, in order to provide for a reliable filling, applies pressure onto the upper side of the filling, the matrix strip is easily displaced laterally so that shearing forces are present within the filling which will negatively effect the quality of the filling.
Even though a deflection of the matrix strip can be avoided by matrix tensioning, the filling result is often such that intensive finishing steps are required. Intensive finishing steps are undesirable with respect to gap formation at the border of the filling because only direct pressure onto the filling allows for a perfect, gap-free connection between filling and tooth. Also, a visual control is possible and the direct pressure application therefore is preferred.
An example for a matrix strip with matrix tensioning device is know from U.S. Pat. No. 5,330,353. In order to improve the edge connection between filling and tooth, it has been suggested to provide the matrix strip with an especially easily bendable shape. Since the tooth shape of different patients and even the tooth shape of different molars and premolars is different, such a special shaping is only a compromise.
It is therefore an object of the present invention to provide a matrix of the aforementioned kind which is especially suitable for filling lateral cavities and which combines an improved manipulation with reduced edge gap formation.